1. Field of the Invention
This invention relates to measuring temperature of integrated circuits and more particularly to a temperature sensor utilized in combination with a heatsink.
2. Description of the Related Art
Processors and other components in modern electronic systems such as personal computers generate significant amounts of heat in operation and therefore require cooling to avoid potentially damaging overheating conditions. For integrated circuits such as processors heatsinks are provided to dissipate heat generated by the processor. Fans are typically utilized in conjunction with heatsinks to blow air on the fins of the heatsink to achieve greater cooling through convection.
In order to determine how much to cooling to apply an integrated circuit device such as a microprocessor, computer systems have typically regulated device temperature by turning a fan on or off, controlling clocks and/or controlling the voltage supplied to the device. In order to properly control temperature, a temperature sensor is utilized that measures the temperature of the integrated circuit so the system can take appropriate action to, e.g., turn on or off the fan, adjust the voltage, or adjust the frequency.
In a testing environment, such as a burn-in environment, in which tests are conducted at elevated temperatures, it can be even more important to obtain accurate thermal information. In certain test environments, it is desirable to hold die temperature within a predetermined range and the temperature sensor has to obtain an accurate die temperature if that goal is to be met. It is therefore desirable for the temperature sensor to be mounted so as to obtain an accurate die temperature. It is further desirable that assembly tolerances of the heatsink and temperature sensor be taken into account.
Accordingly, in order to accurately measure temperature of an integrated circuit device, a temperature sensor, e.g. a thermister, is attached to a compliant or resilient member such as a spring, which in turn is coupled to a heatsink. The heatsink includes a thermal contact surface having a recess. In one embodiment, the recess is a slot extending to an edge of the thermal contact surface. At least a portion of the spring is displaceable within the recess in response to a compressive force. The temperature sensor extends within the slot in the thermal contact surface of the heat sink so that the temperature sensor is centered nominally over the integrated circuit die when the heat sink is abutted against the semiconductor device. The compliant member exerts a force on the temperature sensor to ensure engagement of the temperature sensor with a semiconductor device when the thermal contact surface is abutted against the semiconductor device.
In an embodiment, the recess does not extend to the edge of the thermal contact surface and a high temperature silicone is disposed in the recess and acts as the compliant member. The high temperature silicone exerts a force on the temperature sensor to keep it engaged with a semiconductor device when the thermal contact surface is abutted against the semiconductor device. In addition, the high temperature silicone allows the temperature sensor to be displaced towards the recess when the thermal contact surface is abutted against the semiconductor device.